Compressed gas-operated circuit interrupter with position indicator



Aug. 24, 1948. L. R. LUDWIG EI'AL COMPRESSED GAS-OPERATED CIRCUIT INTERRUPTER WITH POSITION nnucnon Filed play 24, 1944 WITNESSES: gvEmoRs lean l udwlly,

Wade; BY

Patented Aug. 24, 1948 COMPRESSED GAS-OPERATED CIRCUIT INTEBRUPTER WITH POSITION INDI- CATOR Leon R. Ludwig, Forest Hills, and Benjamin P. Baker and James M. Cumming, Turtle Creek, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application Mn! 24, 1944, Serial No. 537,075 11 Claims. (Cl. 177-311) This invention relates to circuit interrupters, and, in particular, to circuit interrupters of the fiuid blast type. More particularly, our invention concerns an improved operating mechanism for a circuit interrupter of the gas blast type.

Certain features disclosed but not claimed in this application are fully disclosed and claimed in copending divisional application, Serial No. 1,546, filed January 10, 1948, by Leon R. Ludwig, Benjamin P. Baker, and James M. Cumming, and assigned to the assignee of the instant invention.

An object of our invention is to provide an improved pneumatically operated interlocking device which will ensure that the opening operation will take precedence over the closing operation.

Another object is to provide an improved structural arrangement for a circuit interrupter of the high voltage type in which the position of the disconnect contact is signalled -by pneumatic means to suitable indicating equipment.

Another object is to provide an improved gas blast circuit interrupter in which suitable interlocking means are provided between the closing air for actuating the disconnect contact and the interrupting contacts. v

Another object is to provide an improved operating arrangement for a gas blast circuit interrupter in which pumping is prevented. Another object is to provide an improved gas blast circuit interrupter operating mechanism in which an'interlocking means is provided so that when closing air is applied opening air will be dumped from the interrupters.

Another object is to provide an improved operating mechanism for a gas blast circuit interrupter in which an improved dumping means is provided for dumping air from the interrupters and also from the disconnect cylinder.

Further objects and advantages will readily become apparent upon a reading of the following specification taken in conjunction with the accompanying drawing, in which the figure shows schematically onehalf of a single pole unit of a high voltage compressed air circuit interrupter embodying our invention and shown in the closed circuit position.

The complete circuit interrupter embodying our invention is shown in a patent application filed May 24,1944, Serial No. 537,074, by Leon R. Ludwig, Herbert J. Webb and Benjamin P. Baker, and assigned to the same assignee as the instant application. The foregoing application not only shows a perspective view of the complete circuit interrupter, but also shows an enlarged view of the interrupting unit for one-half of the pole unit. The present application is concerned with the improved operating arrangement for actuating the aforesaid circuit interrupter.

Referring to the accompanying drawing, the

reference numerals I, 2, and 3 indicate hollow insulator colunms supported on a grounded base structure 4. The column I encloses an, overload current transformer. The column 2 serves to conduct the opening air to the interrupters and the column 3 not only serves to carry the closing air to the disconnect cylinder 5 but also has positioned concentrically therein an inner tube 8, preferably composed of an insulatin material such as glass, to transmit the signalling air from the disconnect cylinder 5 down to suitable indicating equipment 1 contained in the base structure 4. The three insulator columns support a housing I which is preferably made of conducting material and which encloses the operating mechanism for actuating the disconnect contact 9. The disconnect contact In for the other one-half of the pole unit is fragmentarily shown.

Supported on the housing 8 are two insulator columns ll, l2- The column ll encloses the main power interrupter. The column I2 encloses an auxiliary impedance interrupter for interrupting the residual current passing through the resistor l3. At the-top of the column H is an insulating plate I! having an aperture formed therein, the periphery of which is defined by a conducting ring-shaped orifice member l5 which serves as an orifice through which the main power interrupting arc is drawn and through which the blast air for extinguishing said are is forced.

Supported on the insulating plate H is a conducting cylindrical member l5 having a plurality of exhaust apertures I! provided therein which may be closed by a conservator l8 which is spring-biased downwardly by compression springs l9 having their upper seat formed by a conducting cap member 20 having a line terminal 2| rigidly afllxed thereto.

A spider member 22 is supported. by the inner wall of the conducting cylindrical member l8 and serves to maintain in position a stationary contact 23 which may be of the type having segmental conducting fingers biased radially inwardly by a garter spring and which serve to make contacting engagement, in the closed circuit position as shown in the drawing, with a movable main contact 24. The contact 24 is actuated by a piston 25 movable within a conducting cylindrical member 25 having apertures 21 formed therein. The piston 25 is biased upwardly by a compression spring 28; the lower end of which is seated on a ring-shaped plate member 29 rigidly aiiixed to the inner wall of the cylindrical member 26.

The movable contact 24 has an insulating rodshaped extension 30 pivotally connected at 3I to a crankarm 32 which actuates a valve 33.

A resistor R. has portions 11 connected in parallel with the line terminal 2| and the conducting ring-shaped orifice member I and a portion 13 connected in parallel between the ring-shaped orifice member I5 and the conducting cylindrical member 26, the purpose for which will appear more clearly hereinafter.

The cylindrical member 26 has an aperture 34 provided therein which communicates with a conduit 35. The conduit 35 connectsto a conduit 38 having a connection at 31 with the interior of the insulating column l2. The conduit 35 also leads at 38 to the right-hand end 01 the disconnect cylinder 5. The conduit 36 also communicates by means of a conduit39 to a dump valve generally designated by the reference numeral 40. The dump valve 40 may be closed by leftward motion of a slidable piston member 4i spring-biased to the right by a compression spring 42. The piston member All is in communication by means of a conduit 43 with the opening blast pipe III which communicates with the interior of the insulating column II. The dump valve 49 has an exhaust opening at 45 to atmosphere.

The resistor l3 disposed within the insulating column I2 has an upper stationary contact 46 which electrically engages in the closed circuit position with a movable tubular contact 41 having aflixed thereto at its upper end a piston 48 movable within a piston chamber 49 and biased downwardly by a compression spring 50. The

piston chamber 49 has an aperture at 5I which communicates by way of a conduit 52 to the upper side of the conservator I8. A cap member 53 i disposed at the top of insulating column I2.

An overload current transformer generally designated by the reference numeral 54 has its primary winding connected between a point 55 of the housing 8 and a slider connection at 56 making conducting sliding engagement with the disconnect contact 9. The secondary windingoi' the current transformer 54 is connected across a coil 51 actuating an overload contactor generally designated by the reference numeral 58. The contactor 58 has a pair of normally open contacts 59.

The disconnect cylinder 5 has a pair of valves, generally designated by the reference numerals 60 and GI, associated therewith which are opened mechanically by the piston member 62, the latter serving to actuate the disconnect contact 9. The valves 60 and GI are only opened-at the extreme ends of motion of the piston member 52. In other words, valve 60 is only opened when the disconnect contact 9 is at its fully open circuit position. In like manner the valve BI is only opened when the disconnect contact 9 is at its fully closed position.

The valves 60, 6| serve, when opened, to permit communication between the interior of the disconnect cylinder 5 through an aperture 63 through the valves 60 'or 5| to conduits 64, 65

which connect at 66 to lead by way of the insulating tube 6 to a conduit 61. The conduit 61 leads through a valve generally designated by the reierence numeral 68 to the upper end of a piston 4 chamber 59. The conduit 91 also leads by way of a valve generally designated by the reference numeral 10 to the lower end 01 the piston chamber 69. Movable within the piston chamber 59 is a piston II connected by means of a rod 12 to a rotatable switch generally designated by the reference numeral 13. In other words, the rod 12 is pivotally connected at '14 to a rotatable arm 15 pivotally supported at 16 on a fixed pivot.

The arm 15 has a conducting portion 11 and a conducting bridging portion 18. In the closed circuit position of the interrupter the conducting bridging portion 18 electrically connects a long segment 19 to a short segment 80. Also in the closed circuit position or the interrupter the conducting portion 11 makes electrical contact with a short segment 8|. The conducting portion 11 is electrically connected by means or a conductor 82 to two indicating lamps 03, 84. The indicating lamp 83 is connected by means of the conductor 85 to the negative side of the 11-0. power supply for the operating mechanism. The indicating lamp 84 is connected by means of the line 86 to the positive side oi the power supply. The conducting bridging portion 18 is electrically connected to the negative side of the power supply. The reference numeral 81 indicates the source of compressed fluid, in this instance a tank of compressed air. A conduit 88 leads from the tank of compressed air to two electrically actuated valves generally designated by the reference numerals 89 and 90. The valve 89 is actuated by an electrically actuated valve 9|. The valve 90 is actuated by an electricallyactuated valve 92. It is apparent that uponactuation of either valve M or valve 92 compressed air will pass from the chamber 93 through a by-passing conduit 94 to the top side of pistons 95 springbiased upwardly by compression springs 98. Thus, upon actuation of the valves 9|, 92, the pistons 95 will be forced downwardly against the biasing action of the compression springs 96 to open the valves 99, 90 to permit compressed air to pass to either the conduit 91 or conduit 99.

The conduit 91 leads to a chamber 99 having associated therewith a dump valve I00, which is pivotally movable at IOI to a wall of the cylindrical member I02. The dump valve I00, when opened, serves to seat against a seat portion I03 integrally formed with the cylindrical member I02 thereby closing the chamber 99. The dump valve I00, when opened, opens an aperture I04 provided in the cylindrical member I02. The dump valve is pivotally connected at I05 to an actuating rod I06, the right-hand end of which is aflixed to a piston I01 operable within a piston chamber I08. The piston chamber I08 communica-tes by way of the conduit 98 to the upper side of the valve 90. An aperture H0 is provided in the piston chamber I08 which thereby permits communication between the piston chamber I09 and a cylindrical member I I I which communicates with the interior of the insulating column 3. The members III and I02 communicate by conduits Ia and I02a to the columns (not shown) 2 and 3 of the other half of the pole unit.

The operation of the circuit interrupter will now be described. In the closed circuit position or the interrupter as shown in the drawing, the electrical circuit therethrough comprises line terminal 2I, conducting cap member 20, conducting cylindrical member I6, conducting spider member 22, stationary contact 23, movable contact 2i, conducting cylindrical member 26 to conducting housing 8. It will be observed that the electrical circuit through the column I2 is in parallel with the aforesaid circuit. In other words, the electrical circuit through insulating column I2 comprises line terminal 2I, conducting cap member 20, conducting conduit 52, conducting cap member 53, conducting piston chamber 49, conducting piston 48, movable tubular contact 41, upper stationary contact 46, resistor I3, to conducting housing 8.

Thus these two parallel circuits through the columns II, I2 meet at the conducting housing 8 to pass at the point 55 through the primary winding of the overload current transformer 54 to the slider connector 56 to the left-hand movable disconnect contact 9. The circuit then extends through the right-hand disconnect contact I through an identical circuit through the other half of the pole unit (not shown) to the other line terminal of the interrupter.

The following discussion assumes a manual tripping of the circuit interrupter by momentarily pressing the trip button H2. The momentary pressing of the trip button H2 puts the following circuit across the supply system; trip button H2, line H3, line H4, line H5, coil H6, line H1, coil H8, line H9, coil I20, line I2I, long segment 19, conducting bridging portion 18 to the negative side of the supply voltage. This energizes the aforesaid coils. The energization of the coil I20 closes the contactor, generally designated by the reference numeral I22 to thereby cause a circuit to pass through the 'normally open contacts I23 of the contactor I22 to shunt the trip button H2, thus maintaining the aforesaid coils in an energized state following release of the trip button H2. The closing of the contactor I22 opens the normally closed contacts I24 to thereby break biasing action of the springs I9 to permit the blast air to exhaust through the apertures I1 provided in the conducting cylindrical member I6. The compression springs I9 exert only a few pounds pressure on the conservator l8 and since the opening blast air is at a considerably higher pressure, say 250 pounds per square inch, the pressure is sufllcient to force the conservator I8 upwardly to thereby uncover the exhaust apertures I1.

The passage of the blast air upwardly through the orifice member I5 and outwardly though the apertures I1 serves to quickly extinguish the arc drawn between the movable contact 24 and the stationary contact 23. The breaking of this are causes the electrical circuit to pass through the insulator column I2 by way of the movable contact 41, stationary contact 46 and resistor I3. The providing of a parallel resistance path lowers the rate of rise of the recovery voltage across the contacts 23, 24 and lowers the overshoot of the recovery voltage transient.

Since the pressure below the insulating plate member I4 is relatively high and consequently of high dielectric strength, and since the pressure above the plate member I4 is relatively low and consequently of poor dielectric strength, it is desirable to impress a major portion of the voltage between the contacts 23, 24 across the gap between the orifice I5 and the movable contact 24 during the interrupting operation because of the high pressure within the column I I. This is accomplished by the resistor R having a small portion thereof r1 connected in parallel between.

the line terminal 2i and the conducting orifice member I5, and having a larger portion 12 thereof in parallel between the conducting orifice member I5 and the conducting cylindrical memthe circuit through the coils I25 and I26 assuming that the normally open contacts I21, I28 were closed by energization of contactor I35. Thus the opening operation takes electrical precedence over the closing operation by virtue of the fact that the normally closed contacts. I24 are serially connected in the circuit for energizing the closing coil I25.

The energization of the coil I I6 causes an actuation of the electrically actuated valve 9i to thereby cause an opening of the opening valve 89. Compressed air consequently passes from thetank 81 through conduit 88, chamber 93, through opening valve 89, through conduit 91 to chamber 99 to seat the dump valve I00 against the aperture I04 of the cylindrical member I02. The compressed air passing into the cylindrical member I02 acts through conduit I29 to maintain the piston I30 in its upper position, thereby mechanically maintaining the closing valve 90 closed. Thus the piston I30 provides a pneumatic interlock between the opening and closing valves 89, 90 whereby the opening blast of air' will always take pneumatic precedence over the closing air. This results since the area of the piston I30 is greater than the area of the piston 95.

The opening blast air passes upwardly through the insulating column 2 through opening blast pipe 44 to act through conduit 43 to close the dump valve 40. Also the opening blast air passes upwardly into the interior of the insulating column I I to act through the apertures 21 and force the piston 25 downwardly thereby separating the movable contact 24 from the stationary contact 23 drawing an arc therebetween. The opening blast air passes upwardly through the orifice member I5, raising the conservator I8 against the her 26. By the foregoing we have divided the voltage properly through the orifice by causing a greater portion of the voltage to beirnpressed below the orifice and by having the smaller por-- tion of the voltage impressed on the low pressure side of the orifice. g

The low impedance part of the electrical circuit now through the interrupter comprises the line terminal 2|, contact cap 20, conducting conduit 52, cap member 53, piston chamber 49, piston member 48, movable tubular contact 41, stationary contact 46, resistor I3, housing 8, primary winding of current transformer 54, disconnect contact 9 to the right-hand half of the pole unit not shown.

When the piston 25 passes below the aperture 34, opening blast air will pass downwardly through the conduit 35, and since dump valve 40.

is closed at this time will pass to the right through conduit 36 and upwardly into the interior of the column I2 and also to the right-hand end of disconnect cylinder 5. The passage of the opening blast air upwardly within the column I2 will act upwardly on the piston 48 causing the movable tubular contact 41 to move upwardly separating from the stationary contact 46 to establish a residual current arc. The opening blast air will pass through the arc and upwardly through the tubular contact 41, upwardly through the aperture 5i, through the conducting conduit 52 to act downwardly on the conservator I8, thus closing the apertures I1. Thisoccurs because the area of the conservator I8 acted upon by the blast air passing through the conduit 52 is greater than the area of the conservator I8 acted upon by the blast air below the conservator I8. The are is extinguished between the contacts 46, 41

and thereby the residual current passing through the resistor I3 is interrupted.

It will be'observed that downward motion or the piston 25 through extension 30 causes an actuation of the valve 33 to dump the air within the disconnect cylinder 5 to the left of the piston 62. Consequently the opening blast air which passes through conduit 38 into the righthand end of disconnect cylinder 5 causes a leftward movement of piston member 62 and a consequent opening movement of the disconnect contact 9.

The current passing through the resistor I3 is of a relatively low magnitude, say 100 amperes,

' and is thus very easily interrupted with small time delay. As a result the disconnect contact 9 is not moved to the left until after the arc is extinguished within the column i2.

At the end of the leftward motion of the piston member 62, the valve 50 is mechanically actuated and opening air within the disconnect cylinder 5 acts downwardly through aperture 63. through valve 60, conduit 64, tube 6, conduit 81 through electrically actuated valve I (coil H0 now being energized) to act upwardly on the piston II within the piston chamber 69. This causes the rotatable switch I3 to be actuated thereby rotating arm I5 in a counterclockwise direction about pivot point it.

The rotation of the arm I5 causes a separation between the long segment '89 and the conducting bridging portion l8 of arm I5 to thereby break the circuit through the opening coils H8, H8 and I20.

The rotation of the arm I5 to the dotted position indicated by the reference numeral I3I causes contact between the segment i32 and the conducting portion TI of the arm 55. Thus the indicating light 83 is energized, and the circuit through the indicating light 06! is shorted out.

thus darkening the indicating light 85.

The de-energization of coil M3 permits compression spring 96 to raise piston 95 thus closing the opening valve 89. Gradual leakage of air past the conservator It will serve to bring about a reduction in pressure of the air within the column I I. This will permit the compression spring 42 to force the piston member ii to the right thus opening dump valve 49. The opening of dump valve 40 permits air within the column i2 and air to the right of piston member 62 to be dumped. Also the reduction in pressure of the airwithin column it will permit the compression spring 28 to raise the piston 25 and thus cause a re-engagement of contacts 23 and N. Also the reduction of pressure within the column I2 will permit the compression spring 50 to lower the piston 48 and hence effect a re-engagement of the contacts 46, iii.

Thus the two pairs of contacts within the columns H, H reclose following an opening operation and the entire voltage across the circuit interrupter is impressed between the disconnect gap caused by separation of the disconnect contacts 9 and Ill.

The following discussion assumes a normal closing operation with a momentary pressing oi. the closing button I33. The momentary closing of closing button I33 causes an energizaticn of the circuit comprising closing button H33. coil I34 and normally closed contacts. I30 of contactor I31 to the negative side of the supply voltage. This will close the contactor I35 and thereby efiect a closure of normally open contacts I33 of contactor I35. The closure oi contacts I33 causes a lay-passing circuit around the closing button I33 to the positive side of the supply voltage. The closing of contactor I35 eflects a closure of normally open contacts I21, I23. The closure of these latter contacts causes an energization of the circuit which includes contacts I 21, normally closed contacts I24 ot contactor I22. line I33, closing coil I25, line I40, coil I23, line I through closed contacts I23 of contactor I35 to the negative side of the line. The result is an opening of closing valve and also an opening of valve 33.

The opening 01 closing valve 00 permits compressed air to flow from the tank 31 upwardly through conduit 30, through valve 30, through conduit 30 into piston chamber I03 to force piston ill to the left thereby seating the dump valve I00 against the seat portion I03 of cylindrical member I02. Also the closing air passes upwardly out of piston chamber I03 through aperture III and upwardly through column 3. through valve 33 (movable contact 24 being in its raised position) to the left-hand side oi! piston member 62. This closing air forces piston member 02 to the right, the air to the right of the piston member 32 dumping through the dumping valve 40. Disconnect contacts 3 and I0 thus approach each other, engage and thereby eflect a closing of the circuit through the interrupter.

When the piston member i2 is at its fully closed" position, it manually opens valve ii to permit closing air to pass out of the disconnect cylinder 5 downwardly through aperture 63, through valve SI, conduit 65, conduit 5, conduit 01, through valve 60 to the top side of the piston II within the piston chamber 09. This moves the piston member II downwardly eifecting a clockwise rotation of arm I5 about the pivotal point I0 to the position indicated by the full lines in the drawing.

' The separation of segment I32 from conducting portion 11 of arm I5 breaks the circuit which passed through the indicating light 03 and shunted the indicating light 34. Also the engagement of long segment IS with conducting bridging portion I0 of arm I5 causes a circuit to be established through indicating light which comprises the following: negative side of the supply voltage, conducting portion I0, long segment 19, coil I20, coil III, coil iii, line 5, line I42. segment 3i, conducting portion I1, line 32, indicating light 84 to the positive side of the supply voltage. Thus the indicating light 84 lights, but the current passing therethrough is not sufficient to energize the opening coil H8 or coils Ill and 120. The result is that indicating light 83 darkens and indicating light 84 is lighted upon the completion ofthe closing operation of the in terrupter.

Upon the completion of the closing operation the energizing circuit through the closing coils H25. 825 is broken as follows. The engagement of the conducting bridging portion I0 with short segment 30 causes the following circuit to be established: negative side of supply voltage, conducting bridging portion Il, short segment 00, line I40, line I49, coil I50 of contactor I31, line I5I through closed contacts I33 of contactor I35 to the positive side of the supply voltage. Thus contactor I31 closes and contacts I30 thereof open to break the circuit through coil I34 of contactor I35. Contactor I35 then opens and causes opening of contacts I21 and I20. The opening of the latter contacts breaks the circuit through the closing coils I25 and I25. Also the opening of contactor I35 causes contacts I83 thereof to open thereby opening the circuit through the coil I50 of contactor I31. In this and mechanically connected by a rod I45 to the closing valve 90. The right-hand end I40 of the lever I43 moves the end I41 of the rotatable arm 15 to thereby efiect an engagement between the long segment 18 and the conducting portion 18 oi the arm 15. Thus during the initial portion of the closing operation there is provided a possibility of a circuit through the opening coil I I which may be effected upon a closing 01' overload contactor 58 following overload conditions existing in the circuit controlled by the interrupter. In other words, if one is manually closing the breaker during fault conditions, the current transformer 54 will cause a closure of contactor 58 to effect closure of contacts 58. The closure of contacts 59 effects a circuit from the positive side of the supply volta e through contacts 58, line II3, line II4. line H5, opening coil III. line II1, coil Ill, line II8. coil I20, long segment 19, conducting portion 13, to the negative side of the supply voltage.-

Thus b the arm 15 engag ng long'segment 18 during the initial portion of the closing operation, it, is possible to obtain an energization of the opening coil H0 even before the disconnect contacts 9, I0 have eflected a complete engagement. breaker manually on a fault, the opening coil II8 will be energ zed even before the breaker is fully closed. Also the coil I20 will be energized at the same time as the energization of the coil H0 and this will cause a closure of contactor I22 which will open the normally closed contacts I24 to break the circuit through the clos ng coil I 25. The result is that when closing the breaker on a fault the opening coil II8 will take electrical precedence over the closing coil I25 and the breaker will be returned to the fully open circuit position. Naturally the opening sequence of the various parts is as previously described.

Furthermore, when attempting manually to close the breaker on a fault, the passage of compressed air through valve 80 will act through conduit I29 to force piston I30 upward to seal the closing valve 90 closed. This ensures in a pneumatic manner that all the parts of the breaker will move to the open circuit position promptly. The lowering of movable contact 24 will cause rotation of valve 33 to dump closing air out of the disconnect cylinder so that leftward movement of the disconnect piston 52 will not be impeded.

The action of the breaker during high speed reclosing will now be described. Assume the breaker has just been opened during a normal opening operation as explained above, and that it is desired to immediately reclose the breaker. In this condition, however, the air within col-' umns 2, II and I2 will still be at a high pressure, and movable contact 24 lowered. When closing valve 00 is actuated the air pressure passing therethrough will move piston I01 to the left thereby opening dump valve I00. The opening Consequently, it one is clos ng the of dump valve I 00 will dump the air out of columns 2 and II and thereby permit opening of dump valve 40. The opening of dump valve 40 will dump the air out of column I2 and the right end of disconnect cylinder 5. Also the raising of contact 24 will actuate valve 33 to permit communication between column 3 and the left-hand end of disconnect cylinder 5. Consequently, the disconnect contact 9 will be moved to the right to efiect a closing 01 the electrical circuit through the interrupter, the contacts 23', 24 having previously eflected engagement. Thus the circuit is closed on the disconnect contacts 9 and "I0 and not on the contacts 23, 24. From the above it is apparent that the interrupter is operable to always break the circuit on the arcing contacts 23, 24 and 48, 41 and always to close the circuit on the disconnect contacts 3. I0. In the open circuit position of the interrupter the re-engagement of the contacts removes the voltage from the columns I I, I 2 and impresses it across the isolating ap created by separation of the disconnect contacts 9, I0.

The question of "pumping will now be considered. Pumping may be defined as repeated rapid opening and closing operations as a result oi. maintaining the closing button closed during the existence of overload conditions on the circuit controlled by the interrupter. Each time the interrupter is closed, the overload current passing therethrough will actuate the tripping mechanism to return the interrupter to the open circuit position. The maintaining of theclosing button closed will then again cause the interrupter to begin to close. This repeated opening and closing of the interrupter is called pumpi g-1' In the interrupter of our construction this pumping is prevented in a novel manner. To explain how this is done certain assumptions will be made. First, assumethat contacts I52 of contactor I31 and contacts I53 of contactor m are omitted. What is the result? It is apparent that if one maintains the closing button I33 constantly closed, the breaker will be repeatedly moved toward the closed position as long as the contactor I31 is not energized when the breaker is in the open circuit position. For,

it the contactor I31 is energized in the open circuit position, the contacts I36 thereof will break the circuit through the coil I 34 of contactor I35. This will open contacts I21 and I28 to break the circuit through the closing coils I25, I26. Consequently, if contacts I52 of contactor I31 and contacts I53 of contactor I22 are omitted there will result pumping, since contactor I31is not energized in the open circuit position. Secondly, assume that only the contacts I53 of contactor I22 are omitted. What isthe result now? If the breaker moves far enough toward the closed circuit position before tripping takes precedence so that conducting bridging portion 18 of arm 15 engages segment 80, then contactor I31 will be energized. In this event contactor I31 will be maintained in an energized state through contacts I 52 thereof and there will result no pumping, contacts I30 opening the circuit through coil I34 of contactorI35. But if the breaker does not move far enough toward the closed position so that contact is once made between segments 18, to pick up contactor I31, there will result pumping, since contactor I31 will never be energized and coil I84 of contactor I35 will remain energized in the open circuit position of the interrupter.

Now assume that contacts I53 or contactor I22 are present as shown in the drawings. What is the result now? Regardless of the closing travel of the interrupter, and whether or not segments 18, 80 make engagement, once the tripping operation takes place contacts I53 of contactor I22 will energize the contactor I31, and once this contactor is energized it will be maintained in an energized state through its own contacts I52. Since in this state of affairs contactor I3! is energized and maintained energized in the open circuit position 01 the interrupter, the contacts I38 thereof will maintain the contactor I35 in a de-energized state so that closing movement of the interrupter will not take place. Pumping will, therefore, be. prevented. Consequently, by the construction which we show in the drawing, pumping is entirely eliminated.

Although we have shown and described a specific construction, it is 'to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made by'those skilled in the art without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. In a gas blast circuit interrupter, a disconnect contact, a piston operated in a disconnect cylinder for actuating the disconnect contact, signal means indicating the full open and full closed positions of the disconnect contact, pneumatic means interconnecting the signal means and the disconnect cylinder, valve means for controlling the energization oi said pneumatic means to actuate said signal means, and means disposed in said disconnect cylinder engageable by said piston for actuatin said valve means.

2. In a gas blast circuit interrupter, a disconnect contact. a piston operated in a disconnect cylinder for actuating the disconnect contact. a first valve means disposed at one end 01 the disconnect cylinder, a second valve means disposed at the-other end of the di connect cylinder, said piston engaging and o eratin said first and second valve means at its fully open and fully closed positions, and signal means responsive to operation of the first and second valve means to indicate the full open and full closed positions of the disconnect con act.

3. In a gas blast circuit interrupter, disconnect means, operatingmeans for moving said disconnect means to open and closed positions. signalling means comprising a piston chamber and a switch o erable to effect indication of the position of the disconnect means, a piston operable within the piston chamber to actuate said switch, and valve means operated by said operating means only when said disconnect means is in the fully open or fully closed position for admitting compressed gas to said piston chamber to operate said piston.

4. In a gas blast circuit interrupter, disconnect means, pneumatic means for operating said disconnect means, signalling means comprising a mounted switch operable to indicate the position of the disconnect means, a conduit for transmitting compressed gas to the pneumatic operating means to efiect the closing operation of the disconnect means, valve means operable to admit compressed gas to the conduit, an electrical tripping circuit for causing the opening operation of the interrupter comprising a pair of contacts associated with said switch, and means operable by the valve means for actuating the switch to eiIect closure 0! the pair or contacts to prepare said tripping circuit.

5. In a gas blast circuit interrupter, disconnect means, operating means comprising a cylinder and a 'piston operable thereinfor operating said disconnect means to open and closed positions, signalling means comprising a switch movable to two positions to efiect indication of the position of said disconnect means, pneumatic operating means for said signal switch, valve means operable to permit selectively energization of said pneumatic operating means to effect movement of said switch to one position or the other, and valve means operated by said piston only when the disconnect means is in its fully closed and iully open positions'to effect energization of said pneumatic operating means.

6. In a gas blast circuit interrupter, disconnect means, compressed gas operated means for moving said disconnect means to open and closed positions, control valve means comprising an opening control valve operable to admit compressed gas to said interrupter and to said compressed gas operated means to operate said interrupter to the open position and for movin said disconnect means to the open position, a closin control valve operable to admit compressed gas to said compressed gas operated means to move said disconnect means to the closed position, indicating means comprising a switch movable to two positions to indicate the open and closed positions of said disconnect means, pneumatic operating means for said switch, a first valve operable to admit compressed gas to said pneumatic operating means to efl'ect movement of said sw :h to the "open" indicating position, a second valve operable to admit compressed gas to said pneumatic operating means to effect movement of said switch to the closed indicating position, means for actuating said openin control valve and said first valve simultaneously, and means for operating said closing control valve and said second valve simultaneously,

7. In a gas blast circuit interrupter, disconnect means, pneumatic means for operating said interrupter, signalling means comprising a switch operable to indicate the position of said disconnect means, a conduit for transmitting compressed gas to said pneumatic operating means to operate said disconnect means to closed position, valve means operable to admit compressed gas to said conduit, trip means operable whenenergized to cause opening operation of said interrupter and said disconnect means, a tripping electrical circuit for energizing said trip means, and mechanical interlocking means operatively relating said valve means to said switch to automatically actuate said switch upon operation of said valve means to prepare said tripping circuit for energizing said trip means.

8. In a. pneumatic operating mechanism, a main cylinder and a main operatin piston moveable therein between two extreme positions, control valve means comprising a. first inlet valve operable to admit compressed gas to said cylinder to move said piston to one of said extreme positions, a. second inlet valve operable to admit compressed gas to said cylinder to move said piston to a second extreme position, indicating means for indicating the extreme positions of said piston, switch means movable to two positions for energizing said indicating means, operating means for said switch comprising a secondary cylinder and a piston operable therein for actuating said switch, and valve means operable by said main piston only whensaid main piston is moved to its extreme positions for admitting compressed gas to said secondary cylinder to actuate said switch.

9. In a pneumatic operating mechanism, a main operating cylinder and a main operating piston movable therein between two extreme positions, control valve means comprising a first inlet valve operable to admit compressed gas to said main cylinder to move said main piston to one extreme position, a second inlet valve operable to admit compressed gas to said main cylinder to move said main piston to a second extreme position, indicating means for indicating the extreme positions of said main piston, switch means movable to two positions for energizing said indicating 'means, operating means for said switch comprising a secondary cylinder and a piston movable therein for actuating said switch, valve means for selectively admitting compressed gas to said secondary cylinder to actuate said switch, means for actuating said valve means in accordance with the operation of said first and second inlet valves, and valve means operable by said main piston only when said main piston is in said extreme positions to admit compressed gas to said secondary cylinder.

10. In a pneumatic operating mechanism, a main operating cylinder and a main operating piston movable therein between two extreme positions, control valve means comprising a, first inlet valve operable to admit compressed gas to said main cylinder to move said main piston to one extreme position, a second inlet valve operable to admit compressed gas to said main cylinder to' move said main piston to a second extreme position, indicating means for indicating the extreme position of said main piston, switch means movable to two positions for energizin said indicating means, operating means for said switch comprising a secondary cylinder. and a piston movable therein for actuating said switch, valve means disposed at opposite ends of said secondary cylinder and operable to admit compressed gas to said secondary cylinder to actuate said switch to its two positions, means for simultaneously actuating said first inlet valve and the valve at one end of said secondary cylinder, means for simultaneously actuating said second inlet valveand the valve at the other end of said s condary cylinder, and

valve means disposed in said main cylinder to be engaged and operated by said main piston only when said main piston nears its'extreme positions to admit compressed gas to said secondary cylinder.

11. A gas blast circuit interrupter comprising disconnect means, a cylinder and a piston operable therein for operating said disconnect means, signalling means, pneumatic means for operating said signalling means, a first conduit for transmitting compressed gas to said cylinder to effect an opening operation of said disconnect means, a

second conduit means for transmitting com- REFERENCES CITED The following references are of record in the filo of this patent:

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